Yea!Cops do and “shall not be infringed”
Okay, so the stadium is a private entity, correct?
Certainly the potential discharge of firearms in a dense crowd, even by police, can be problematic in some cases. Perhaps a friendly and courteous "check firearms at the door" policy might be an option.
Regardless, the stadium ownership is (or should be) at liberty to set firearms policies as it sees fit.
The market decides the rest...